Care of your Tomato Plants

Planting time

Any old-time gardener will not plant tender crops such as tomatoes, peppers, cucumbers, squash, corn, and beans until the 24th of May.  This is still a good rule of thumb for our region of central Vancouver Island.  If you have some frost protection it is probably safe to plant out in the early part of May.  (An over-night low of -2.2°C was recorded at Campbell River on May 27/66 and Comox Airport recorded a low of 0.5°C on June 5/88, so there are no guarantees).  Frost or no frost, your plants will not thrive if they are shivering.

Plant type

There are three major categories of plant growth types:

  1. Indeterminate:  Indeterminate tomato plants continue to grow, limited only by the length of the season. These plants produce stems, leaves, and fruit as long as they are alive.  These plants perform best if staked and pruned.  Some indeterminate varieties are:  Early Girl, Big Beef, Sweet Cluster, New Girl, Money Maker, Len's Prize, Lemon boy, Joan's Roma, Sun Sugar, Sweet Baby Girl, and most "heritage" varieties.
  2. Determinate:  Determinate tomato plants have a predetermined number of stems, leaves, and flowers hardwired into their genetic structure.  The major advantage of planting determinate plants in a home garden is early harvest.  These plants do not have to be pruned but perform better if the lower suckers are removed and have some support to keep them off the ground.  Some determinate varieties are:  Bush Beefsteak, Polfast, Fantastic, Lunch Box, Oregon Spring, and most Roma types.
  3. Bush or Dwarf:  These plants are best for growing in containers.  Most of the fruit is formed on sucker growth so these plants should not be pruned.  Some bush or dwarf varieties are:  Tumbler, Patio, Totem, Gold Nugget and Red Alert.

Pruning

With tomatoes, we want to maximize the efficiency of photosynthesis and minimize the risk of disease. This is best accomplished by ensuring that each leaf has plenty of room and is supported up off the ground.  Pruning methods vary with the plant type.Joan's Roma

  1. Indeterminate:  Remove all suckers as they appear.  In the diagram to the right, the sucker is the branch that appears between the  main stem and the leaf.  It is much easier to remove these suckers when they are small.  Be careful not to remove main growing tip at the top of the plant.  Once fruit starts to form, we remove all leaves below the fruit for ease of picking and to allow air circulation around the plant.  The picture to the left shows some pruned Joan's Roma plants in mid August with all the lower branches removed.  We do not top the plants until early to mid September unless the plant is so tall the fruit is beyond our reach.  Remove all dead or diseased leaves and discard away from the area.  Ideally, there shouldn't be all those weeds growing but this just shows that you don't have to be perfect to grow good tomatoes!

  2. Determinate:  Determinate plants can be just left with no pruning but the quality of the fruit and the health of the plant will benefit from some care.  The most important thing is to get the plants off the ground by using a cage or some other support.  Most of the pruning is done after the first flower cluster appears.  We remove the lower suckers up to the one below the lowest flower and then leave it alone except for removing any branches that start to touch the ground.  As with the indeterminate plants, if there are any dead or dying leaves, we remove them and discard them away from the tomato patch.

  3. Bush or Dwarf plants:  Do not prune!  The leaves from the original part of the plant start to curl as they get older and will turn yellow and die eventually.  We usually remove the curled leaves if they become too unsightly and clear any dead growth from around the plant.

Tomato Diseases

Most modern tomato varieties are resistant to many diseases common to tomatoes.  There are two weather-related problems that crop up in tomatoes in our west coast climate:
Blossom End Rot Blossom-end Rot:  Many people confuse this condition with blight, but blossom-end rot is not a disease that is passed from plant to plant.  It starts out as a green-gray watermark on the bottom (blossom end) of the fruit and eventually turns into a flat or concave leathery patch which can turn black and spoil the entire fruit.  Blossom-end rot is induced when demand for calcium exceeds supply. This may result from low calcium levels, drought stress, or excessive soil moisture fluctuations which reduce uptake and movement of calcium into the plant, or rapid, vegetative growth due to excessive nitrogen fertilization.  The addition of lime to the soil before planting and consistent watering, especially during hot spells, can help to prevent this condition.
Late Blight Late Blight:  The first sign of late blight usually appears as a dark lesion on the stem of the plant which spreads to the leaves and quickly spreads to the fruit.  Fifteen years ago, after several cool, wet summers, it was almost impossible to grow tomatoes outdoors in the Comox Valley.  Overnight what promised to be a bumper crop of tomatoes turned into a rotten mess.  The warm, dry summers that we have enjoyed for the past few years has helped to eradicate the spores of this disease, but we should be aware that late blight can still raise its ugly head.  The best way to prevent blight is to keep your plants dry and well ventilated.  We erected our first greenhouse after losing a crop to late blight in 1993.  If blight should occur in your garden, remove all fruit and plant material and do not plant tomatoes (or peppers, eggplant, and potatoes) in that area the following year

Harvest

Wait until your tomatoes are fully ripe and pick with the little stem attached.  At the end of the season and frost is imminent, mature green fruit can be harvested and ripened indoors.  Ripe and green fruit should not be refrigerated as tomatoes lose their flavour and texture if they are kept too cold.  Remember to enjoy the fruits of your labour; there is nothing like the taste of a vine ripened tomato still warm from the sun.


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Page updated:  February 26, 2009